In a multi-investigator, multi-project Program Project, a number of scientific and administrative support activities are required. These are best provided in a centralized fashion rather than attempting to fragment them according to a particular project and/or investigator, especially when there are many areas of overlap. The Support Core provides such centralized approaches and is based on two components. The analytical component will provide support to the various Projects for the structural, qualitative and quantitative analysis of drugs and metabolites. Gas chromatography/mass spectrometry analyses will be performed with high sensitivity an specificity by the use of stable isotope dilution methodology in combination with electron capture negative chemical ionization. Liquid chromatography/electrospray ionization tandem mass spectrometry will be employed for the identification of drug metabolites. Alternative mass spectrometry methodology that employs electron ionization, positive chemical ionization, liquid secondary ion, matrix-assisted laser desorption is available should it be required. This component will also provide a resource for the synthesis of drug metabolites and stable isotope analogs for use as standards for stable isotope dilution assays. Analytical procedures that require conventional HPLC methodology will be developed in the Core if they are required in the individual projects. An administrative component will provide the structure to support essential but non-scientifically related activities for the individual Projects. For example, administrative coordination, fiscal management, ordering of supplies, manuscript and grant-report preparation, and the provision of common services such as duplicating, services contracts, mailing and travel support, etc. In addition, biostatistical support for all of the Projects will be provided by the Core.